As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU HAS HISTORY OF FAULT LIGHT ILLUMINATING DURING START WITH NO FLAME SHUTDOWN FAULTS BEING LOGGED. PREVIOUS MAINT IGNITION LEAD AND PLUG REPLACED. ACFT GROUNDED. R & R THE APU IGNITION UNIT. IAW AMM 49-41-31/401, OPS CHECKS NORMAL. NO CURRENT APU FAULTS.